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THE BULL TROUT (SALMO ERIOX). 



By J. A. ERSKINE-STUART, L.R.C.S.E., 



Healey, -iiear Batley; President of the Heckmondwike Naturalists' Society. 



Writing in the Naturalist for October 1884, the Rev. M. G. Watkins 

 asks some one to take up the interesting subject of the Bull Trout, a 

 very important salmonoid found in many of our rivers, more especially 

 the Tweed. As a native of Tweedside, I have been acquainted with 

 this fish from boyhood, and was certainly surprised to find that 

 Giinther and other eminent ichthyologists were of opinion that all 

 the so-called members of the Salmo eriox species might be referred 

 to the Salmo trutta or Sea Trout. I shall endeavour, shortly and 

 succinctly, to lay before your readers what can be said for giving the 

 Bull Trout specific rank. That there are many structural differences 

 between the Sea and Bull Trout I cannot maintain, but the habits 

 and distribution of the two fish are so different that, apart altogether 

 from structural peculiarities, the Salmo eriox may be accounted a 

 true species. The characters, structural and otherwise, on which my 

 opinion is based are as follows : — The Sea Trout (Salmo trutta) never 

 exceeds 6 lbs. in weight, its flesh cuts red at every season of the year, 

 its gill-cover (operculum) is slightly tuberculated on its posterior 

 margin, and the teeth on the vomer are more persistent and more 

 numerous than in the 5. salar and S. eriox ; the tail is slightly forked 

 when young, becoming ultimately square in the adult, and is shorter 

 and smaller than in the other Salmonoid. The Bull Trout (Salmo eriox), 

 on the other hand, runs as high as 20 lbs. to 30 lbs. in weight, its flesh 

 never cutting red at any time of the year, but being yellowish even at the 

 height of the season ; the posterior border of the gill-cover is rect- 

 angular, and the teeth are longer and stronger than in either the 

 5. salar or S. trutta, the vomerine teeth being in the adult nearly all 

 lost. The Bull Trout jaw is almost as villainous looking as that of 

 a small shark. The Sea Trout will take the fly freely at all stages of 

 its growth, while the Bull Trout will only take it when in the grilse 

 and kelt stages — especially in the latter, when it is ravenous. Sea 

 Trout are usually found in short tidal rivers communicating with 

 lochs, such as are found in the West Highlands. Bull Trout, on the 

 other hand, are generally found in rivers with a long course, and not 

 influenced by the tide; and where they abound Sea Trout are rarely 

 seen, as for instance in the river with which I am best acquainted, 

 the Whitadder, a tributary of the Tweed, in Berwickshire. Probably 

 the Bull Trout is better known in the Tweed and tributaries than in 

 any other river (Pennell), and therefore it is good ground for observ- 

 ing the habits of this fish. The latest authority evidently leans 

 towards giving the Bull Trout specific rank, for he says : — ' Some 



Oct. 1885. 



